Structural and Catalytical Features of Different Amylases and their Potential Applications

Abstract

Amylases can hydrolyze the O-glycosyl linkage of starch and related polymers. They are ubiquitously present in all living systems. However, microbial amylases meet the demands of industrial applications. Amylase and related enzymes are classified in different glycosyl hydrolases (GH) families. The GH13 is the largest family in the carbohydrate-active enzyme (CAZy) database, which comprises α-amylase, α-glucosidase, maltogenic amylase, debranching enzymes, CGTase, pullulanase, neopullulanase, and others. Despite GH13, some other families also contain α-amylase and related enzymes. Most of the starch-degrading enzymes have a common (β/α)8 barrel structure and four or five conserved sequences containing catalytic residues. α-Amylase and related enzymes follow the α-retaining double displacement mechanism during catalysis. The enzymes of the α-amylase family are potentially applied in food, pharmaceutical, textile, paper, detergent, biofuel, and animal feed producing industries. α-Amylase-mediated liquefaction and saccharification of starch is the essential step for the production of glucose, maltose, high fructose-containing syrups, maltooligosaccharides, cyclodextrins. These products are potentially used for the preparation of geriatric and infant foods. In conclusion, starch degrading enzymes bear a common structural arrangement and catalytic activity, and are broadly exploited in different sectors ranging from food, pharmaceutical industries to wastewater treatment.